For years, CCleaner has been our go-to application for safely clearing temporary files, unused and invalid Registry entries, and Internet tracks. The self-proclaimed "crap cleaner" does what it says without much fuss and with a few extra configuration options.
With the exception of applying its scrubbing efforts to Firefox 3.0, the latest CCleaner update is predominantly a bug-fixing and minor tweaking release. There are back-end changes to fix bugs that skipped over a few Internet Explorer cookies, to improve the application's internal memory, and to keep the CCleaner icon from getting locked into the system tray. A bug on the uninstaller tool on the 64-bit version has also been corrected, and there are minor tweaks to the program interface.
The interface, incidentally, is one area I'd personally like to see freshened up. Call me shallow, but from a design standpoint, CCleaner has paraded its horizontal pinstripe look for too long.
First-time CCleaner-users should pay attention to the program check boxes during installation. With two shortcuts, Recycle Bin buttons, and a browser toolbar, the application's default extras can get a bit much. For me, the application and Start menu shortcut are sufficient; though since I use Launchy to quickly open applications, the latter isn't even necessary.